Ann Romney said she had health 'scare' before Super Tuesday

"There have been some days, like before Super Tuesday, I was quite fatigued, and I knew I couldn't quit. I didn't tell anybody I was tired," Romney said in an "Entertainment Tonight" interview that will air Thursday. 

Romney added that she "kept going" even when she was experiencing warning signs, which led to "a little bit of a scare."

“You know, what happens with me is that I start to almost lose my words. I almost can't think. I can't get my words out. I start to stumble a little bit and so those things were happening and I thought, 'Uh oh, big trouble,' " she said.

Romney was diagnosed with the autoimmune disease, which affects the central nervous system, in 1998. She has spoken about her struggles with the disease on the campaign trail; during a speech Monday night, she heralded her husband for having "stood by my side" when she was diagnosed.

Supporters have often cited the disease as evidence of a challenge Romney overcame, especially in the aftermath of Democratic strategist Hilary Rosen's comments about her having "never worked a day in her life."

"I know what it’s like to struggle and to have those concerns that all mothers have,” Romney said Monday.